ASTM D4829-2008a Standard Test Method for Expansion Index of Soils《土壤的膨胀系数的标准试验方法》.pdf

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1、Designation: D 4829 08aStandard Test Method forExpansion Index of Soils1This standard is issued under the fixed designation D 4829; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses

2、indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method allows for determination of expansionpotential of compacted soils when inundated with distilledwater.21.2 This test method provides a simpl

3、e yet sensitive methodfor determination of expansion potential of compacted soils forpractical engineering applications using an index parameter.1.3 The values stated in SI units are to be regarded as thestandard. The values stated in inch-pound units are approxi-mate.1.4 All observed and calculated

4、 values shall conform to theguidelines for significant digits and rounding established inPractice D 6026.1.4.1 The method used to specify how data are collected,calculated, or recorded in this standard is not directly related tothe accuracy to which the data can be applied in design or otheruses, or

5、 both. How one applies the results obtained using thisstandard is beyond its scope.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and

6、determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3D 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12 400 ft-lbf/ft3(600kN-m/m3)D 854

7、Test Methods for Specific Gravity of Soil Solids byWater PycnometerD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2435 Test Methods for One-Dimensional ConsolidationProperties of Soils Using Incremental LoadingD 3740 Practice for Minimum Requi

8、rements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD 3877 Test Methods for One-Dimensional Expansion,Shrinkage, and Uplift Pressure of Soil-Lime MixturesD 4753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Mas

9、ses for Use in Soil, Rock, andConstruction Materials TestingD 6026 Practice for Using Significant Digits in Geotechni-cal DataE11 Specification for Wire Cloth and Sieves for TestingPurposesE 145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Terminology3.1 For common definitions

10、 of other terms used in this TestMethod, refer to Terminology D 653.3.2 Definitions:3.2.1 scarificationscratching the surface of a compactedlayer to facilitate bonding with the next layer to avoid potentialseparation between compacted layers.3.3 Definitions of Terms Specific to This Standard:3.3.1 e

11、xpansion index (EI), n1000 times the differencebetween final and initial height of the specimen divided by theinitial height.4. Summary of Test Method4.1 A specimen is prepared by compacting a test soil into ametal ring at a degree of saturation of 50 6 2 %. The specimenand the ring are then placed

12、in a consolidometer. A verticalconfining pressure of 6.9 kPa (1 lbf/in.2) is applied to the1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved Dec. 1,

13、 2008. Published January 2009. Originallyapproved in 1995. Last previous edition approved in 2008 as D 4829 08.2Refer to Anderson, J. N., and Lade, P. V., “The Expansion Index Test,”Geotechnical Testing Journal, Vol 4, No. 2, ASTM, 1981, pp. 5867.3For referenced ASTM standards, visit the ASTM websit

14、e, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor D

15、rive, PO Box C700, West Conshohocken, PA 19428-2959, United States.specimen and the specimen is then inundated with distilledwater. The deformation of the specimen is recorded for 24 h oruntil the rate of deformation becomes less than 0.005 mm/h(0.0002 in./h), whichever occurs first. A minimum recor

16、dingtime of3hisrequired.5. Significance and Use5.1 The expansion index, EI, provides an indication ofswelling potential of a compacted soil.5.2 The EI test is not used to duplicate any particular fieldconditions such as soil density, water content, loading, in-placesoil structure, or soil water chem

17、istry. However, consistent testconditions are used in preparation of compacted specimenssuch that direct correlation of data can be made betweenorganizations.NOTE 1Qualitative classification of potential expansion in a soilbased on EI is provided in Table 1.NOTE 2Notwithstanding the statements on pr

18、ecision and bias con-tained in this test method: The precision of this test method is dependenton the competence of the personnel performing it and the suitability of theequipment and facilities used.Agencies which meet the criteria of PracticeD 3740 are generally considered capable of competent tes

19、ting. Users ofthis test method are cautioned that compliance with Practice D 3740 doesnot ensure reliable testing. Reliable testing depends on several factors;Practice D 3740 provides a means of evaluating some of those factors.6. Apparatus6.1 MoldThe mold shall be cylindrical in shape, made ofmetal

20、, and shall have the capacity and dimensions indicated inFig. 1. The mold shall have a detachable collar inscribed witha mark 50.8 mm (2.00 in.) above the base. The lower section ofthe mold is designed to retain a removable stainless steel ring25.4 mm (1 in.) in height, 101.9 mm (4.01 in.) in intern

21、aldiameter, and not less than 3.10 mm (0.120 in.) in wallthickness.6.2 RammerA metal rammer with a circular face with adiameter of 50.8 mm (2.00 in.) and a mass of 2.5 kg (5.5 lbm)shall be used. The rammer shall be equipped with a suitablearrangement to control height of drop to a free fall of 304.8

22、 mm6 1.3mm (12 in. 6 0.05 in.) over the top of the soil to becompacted. SeeTest Methods D 698 for further specification ofa suitable rammer.6.3 BalanceAbalance of at least 1000 g capacity meetingthe requirements of Guide D 4753, Class GP2.6.4 Drying OvenA thermostatically controlled dryingoven (spec

23、ified in Specification E 145) capable of maintaininga temperature of 110 6 5C (230 6 9F) for drying watercontent samples.6.5 Straight EdgeSteel straight edge at least 150 mm (6in.) in length with one beveled edge.6.6 SievesA 4.75-mm (No. 4) sieve conforming to therequirements of Specification E11.6.

24、7 Mixing ToolsMiscellaneous tools such as mixingpans, spoons, trowels, spatula, a suitable mechanical device,and so forth for thoroughly mixing the sample of soil withwater.6.8 Loading DeviceA consolidometer or equivalent load-ing device as described in Test Methods D 2435 for supportingand submergi

25、ng the specimen, for applying a vertical load, andfor measuring the change in height of the specimen. Theconsolidometer ring must be as specified in 6.1.6.9 Porous DisksThe disks shall be smooth ground andfine enough (Note 3) to minimize intrusion of soil into thedisks. The disk shall reduce false d

26、isplacements caused byseating of the specimen against the surface of the disk. Suchdisplacements are significant, especially if displacements andapplied vertical pressures are small.NOTE 3A suitable pore size is 10 m.6.9.1 Porous disks shall be air dry.6.9.2 Porous disks shall have a close fit to th

27、e consolidom-eter ring to avoid extrusion or punching. Suitable disk dimen-sions are 12.7 mm 6 0.13 mm (0.50 in. 6 0.005 in.) in heightand 101.5 mm 6 0.13 mm (3.995 in. 6 0.005 in.) in diameteror as described in 6.3 of Test Methods D 2435.7. Sample Preparation7.1 Preparation for SievingIf the soil s

28、ample is dampwhen received from the field, dry it until it becomes friableusing a trowel. Air drying or oven drying at temperaturesbelow 60C (140F) may be used. Thoroughly break up theaggregations in a manner such that the natural size of indi-vidual particles is not reduced.NOTE 4If particles large

29、r than 6.35 mm (0.25 in.) are potentiallyexpansive, such as particles of claystone, shale, or weathered volcanicrock, they may be broken down so as to pass the 4.75-mm (No. 4) sieveif this is consistent with use of the soil.7.2 SievingSieve an adequate quantity of the representa-tive soil using the

30、4.75-mm (No. 4) sieve. Record the percent-age of coarse material retained on the 4.75-mm (No. 4) sieveand discard.7.3 SampleSelect a representative sample of the soil witha mass of approximately 1 kg (2 lbm) or more prepared usingthe guidelines in 7.1 and 7.2.8. Specimen Preparation8.1 Water Content

31、Thoroughly mix the selected represen-tative sample with sufficient distilled water to bring the soil toa water content that has a corresponding degree of saturation of50 6 2 % in the compacted condition. After mixing, take arepresentative sample of the material for determination of thewater content

32、and seal the remainder of the soil in a close-fitting airtight container for a period of at least 16 h. Weigh themoisture sample immediately, and dry in an oven at 110 6 5C(230 6 9F) for at least 12 h, or in accordance with TestMethods D 2216, to a constant mass. The water content sampleshall have a

33、 mass of at least 100 g conforming with TestMethods D 2216. The water content of the trimmings shall beTABLE 1 Classification of Potential Expansion of Soils Using EIExpansion Index, EI PotentialExpansion020 Very Low2150 Low5190 Medium91130 High130 Very HighD 4829 08a2determined in accordance with T

34、est Methods D 2216 using aresolution of 0.1 % or better.8.2 Specimen CompactionPrepare a specimen by com-pacting the cured soil in the 101.9-mm (4.01-in.) diametermold in two equal layers to give a total compacted depth of50.8 mm (2 in.). Compact each layer by 15 uniformly distrib-uted blows of the

35、rammer dropping free from a height of 305mm 6 2.5 mm (12 in. 6 0.1 in.) above the top of the soil whena sleeve type rammer is used, or from 305 mm 6 2.5 mm (12in. 6 0.1 in.) above the approximate elevation of each finallycompacted layer when a stationary mounted type of rammer isused. Scarify the fi

36、rst compacted layer before adding materialfor the second layer using a knife or other suitable object.During compaction rest the mold on a uniform rigid founda-tion, such as provided by a cube of concrete with a mass notless than 90 kg (200 lb).8.3 Specimen TrimmingFollowing compaction, removethe up

37、per and lower portions of the mold from the inner ringand carefully trim the specimen flush with the top and bottomof the ring with a straight edge.8.4 Specimen HeightDetermine the initial height of thespecimen H1, with a resolution of 0.03 mm (0.001 in.) similarto the procedure in Section 7 of Test

38、 Methods D 3877 orassume equal to the height of the specimen ring.8.5 Degree of SaturationCalculate the water content inaccordance with Test Methods D 2216 and the dry unit weightin accordance with Section 11 of Test Methods D 698. Deter-mine the degree of saturation using the equation providedbelow

39、. If the degree of saturation is not within 50 6 2%,prepare another specimen. Adjust the water content of the newspecimen based on the calculated degree of saturation andprepare the specimen in accordance with 8.1-8.4 to achieve adegree of saturation 50 6 2 %. Increase the water content if thedegree

40、 of saturation is less than 50% and decrease the watercontent if the degree of saturation is higher than 50 %.S 5wGsgdGsgw2gd(1)where:S = degree of saturation, %w = water content, %,Gs= specific gravity, use 2.7 unless the specific gravity isknown to be less than 2.6 or more than 2.8,gw= unit weight

41、 of water, 9.79 kN/m3(62.3 lbf/ft3) at 20C(68F), andgd= dry unit weight of compacted soil specimen, kN/m3(lbf/ft3).Use the resolution provided in 8.1 for w. Use a resolution of0.1 kN/m3(0.1 lbf/ft3) or better for gd.NOTE 5This standard test method assumes a specific gravity of 2.7,which is typical o

42、f soil minerals commonly used for compaction. Inaddition, using an assumed specific gravity value of 2.7 will result in amaximum error of 4 % in the calculated degree of saturation, provided theactual specific gravity is between 2.6 and 2.8. These small errors insaturation with mineral type will cau

43、se systematic and small changes inthe EI that are considered equally important to variations caused whendetermining the specific gravity using Test Methods D 854.9. Procedure9.1 Place the compacted soil specimen in the ring of aconsolidometer or equivalent loading device with air-driedporous disks p

44、laced at the top and bottom ends of thespecimen. Subject the specimen to a total pressure of 6.9 kPaFIG. 1 Mold with Ring for Compaction of Specimen forExpansion Index TestD 4829 08a3(1 lbf/in.2), including the weight of the upper porous disk andany unbalanced weight of the loading machine. Allow th

45、especimen to compress under this pressure for a period of 10min. Subsequent to this initial compression period, obtain theinitial reading (D1) on the consolidometer dial indicator with aresolution of 0.03 mm (0.001 in.) or better.9.2 Inundate the specimen with distilled water, obtainingperiodic dial

46、 indicator readings, in accordance with TestMethods D 2435, for a period of 24 h or until the rate ofexpansion becomes less than 0.005 mm/h (0.0002 in./h).However, in no case shall the sample be inundated andreadings taken for less than 3 h.9.3 Remove the specimen from the loading machine afterthe f

47、inal reading (D2) obtained with a resolution of 0.03 mm(0.001 in.) or better and determine the change in height DH asthe difference between the initial and final reading of the dialindicator. Determine the specimen mass to the nearest 0.1 g(2.2 3 104lbm).10. Calculation and Report10.1 CalculationCal

48、culate the expansion index, EI,asfollows:EI 5DHH11000 (2)where:DH = change in height, D2D1, mm,H1= initial height, mm,D1= initial dial reading, mm, andD2= final dial reading, mm.Use the resolutions provided in 8.4, 9.1, and 9.3 for H1, D1,and D2, respectively.10.2 Record as a minimum the following g

49、eneral informa-tion (data):10.2.1 Sample/specimen identifying information, such asProject No., Boring No., Sample No., Depth, and so forth.10.2.2 Any special selection and preparation process, suchas breaking down large particles of claystone, shale, volcanicrock, and so forth.10.3 Record as a minimum the following specimen data:10.3.1 The initial height (use a resolution of 0.03 mm (0.001in.) or better).10.3.2 The initial water content (nearest 0.1 %).10.3.3 The initial dry unit weight (use a resolution of 0.1kN/m3(0.1 lbf/ft3) or better